I'll add my $0.02 here -- I exclusively bought these Chinese fountain pens for a while, before I upgraded to some better ones (like TWSBI Eco).

My experience was that these ultra-cheap Chinese pens are fun to play with, but extremely unreliable. The number-one issue was that they'd dry up after a day without use, which renders them annoying as writing tools (but they're still fun to look at and play with!)